You have good reason to be concerned by this sudden turn of events. Any shortness of breath of sudden onset, to this degree, in a previously healthy woman must be taken seriously and it could be the result of heart disease (including abnormal heart rhythms) or a whole variety of lung diseases, some quite serious and the overwhelming majority of them being quite treatable. Lung problems to be considered in a previously healthy person your age would include asthma or other obstruction to airflow in and out of your lungs, air leakage from the lung (pneumothorax) resulting in collapse of the lung, infectious and non-infectious pneumonias and the most serious of all, blood clots to the lung.
There are other causes as well, but given the serious possibilities I have just mentioned, it is imperative that you see a doctor without further delay and that whoever you see give careful attention to your symptoms, in a manner they deserve, until the cause is determined. In short, if you have not already seen a doctor and had your condition diagnosed and treated, you should seek medical attention urgently, with no further delay.
The good news is that most of the causes of your symptoms are diagnosable and treatable, but there is no time to waste in you and your doctors getting to the heart of the matter.
Good luck
